The disclosures herein relate generally to computer systems and more particularly to an electromagnetic emission shielding apparatus for a portable computer hinge assembly.
To generate an image on a display of a portable computer, electrical signals and power are routed between a top enclosure and a base enclosure of the computer. Currently, many portable computers use a display interconnect circuit, such as a flexible circuit, to electrically connect the base enclosure of the computer to the top enclosure. Display interconnect circuits typically include a dielectric substrate with multiple conductive traces mounted thereon for routing power, ground and signals from the base enclosure to the top enclosure. In addition to routing signals and power between the base enclosure and the top enclosure, display interconnect circuits must also accommodate the movement of the top enclosure relative to the base enclosure.
In general, display interconnect circuits include a display routing portion, a base routing portion and a spanning portion extending therebetween. The spanning portion electrically connects the display routing portion to the base routing portion. The spanning portion also accommodates the movement of the top enclosure of the computer relative to the base enclosure.
To reduce the potential for electromagnetic interference (EMI) with adjacent electronic devices, EMI shielding must be provided for portions of the circuit that are susceptible to electromagnetic emissions. Similar to the operating speed of microprocessors, the operating speed of video controllers continues to increase. High-speed video signals such as Low Voltage Differential Signaling (LVDS) signals are approaching signal speeds at which electromagnetic emission must be addressed. The magnitude of these speeds may result in electromagnetic emissions at the spanning portion of the display interconnect circuit.
The spanning portion of display interconnect circuits are particularly susceptible to electromagnetic emissions. The space and orientation that the spanning portion must accommodate within the computer often require that the circuit design rules for limiting electromagnetic emissions be violated. The spanning portion of a display interconnect circuit also extends adjacent to discontinuities defined by the hinge assembly that connects the top and base enclosures of a portable computer. The potential for electromagnetic emissions, particularly through the discontinuities, is increased when high speed video signals are carried by the spanning portion of the display interconnect circuit.
U.S. Pat. No. 5,978,210 discloses a display interconnect circuit including a spanning portion that is wrapped around a bobbin assembly. The bobbin assembly includes a core member and a removable cover member mounted on the core member. Shielding may be provided by a separate shielding member that shrouds the portion of the circuit that is wrapped around the core member of the bobbin assembly. The bobbin assembly and separate shielding member represent additional components that must be assembled on the production line during assembly of the computer, increasing manufactured cost of the computer.
Therefore, what is needed is a simple and cost-effective shielding apparatus for containment of electromagnetic emissions from the spanning portion of an interconnect circuit at the hinge assembly of an electronic device.